The Tribune Co.-owned station, which broadcasts at 720 AM, has reached an agreement to run 87.7 FM through a lease agreement, and will launch a new format on Monday afternoon.

The deal coincides with the end of an alternative music simulcast currently being aired with 101.1 FM. While the new format has not been disclosed, executives confirmed Friday that Jonathon Brandmeier will host the morning show on 87.7 FM.

The local marketing agreement with Los Angeles-based Venture Technologies Group, which owns the frequency, will run through September 2015, according to executives.

Technically a low-powered TV station, 87.7 FM became available after Cumulus Media struck a deal last month to acquire former Tribune Co. CEO Randy Michaels' Merlin Media. Cumulus took over operations of WLUP-FM 97.9 (The Loop) and WIQI-FM 101.1 through a four-year local marketing agreement, with a firm option to buy the stations.

As part of the deal, the alternative rock format airing on WKQX-FM 87.7, migrated back to its former home on 101.1 FM, along with the call letters. The new call letters for 87.7 will be WGWG-LP, according to executives.

When veteran Chicago radio executive Jimmy de Castro took the helm of WGN-AM 720 in June, he re-engineered the legacy station, bringing back a number of WGN alumni including Steve Cochran and Kathy & Judy. He also shifted Brandmeier, who joined WGN in 2011, to a new virtual FM station — wgnfm.com — while looking to acquire an FM frequency in the market. Brandmeier’s show will be simulcast on 87.7 FM and online, according to executives.

WGN's pursuit of an FM station is limited by Federal Communications Commission cross-ownership rules, which prohibit owning a newspaper and radio station in the same market. Tribune Co.’s co-ownership of WGN Radio and the Chicago Tribune predates that rule, and the impending spinoff of its newspaper business may open the door to future acquisitions.